Influence of vascular smooth muscle on contractile mechanics and elasticity of arteries.

DOBRIN, PHILIP B., AND ALLEN A, &NICK. hj%ence of mmlmsmooth muscle on contractile meclzanics and elasticity of arteries, Am, J. Physiol. 2 17(6) : 1644-1651. 1969.---Segments of canine carotid artery were held at in situ length and studied in vitro after treatment with norepinephrine (NEpi) and after treatment with potassium cyanide (KCN). Activation of the vascular muscle caused contraction and greatly increased pressure-radius hysteresis, The blood vessel muscle exhibited an active stress-strain curve u:ith a maximum stress of .88 it: .10 x lo6 dynes/cm2 for the whole wall, or 2.73 X 10” dynes/cm2 for the estimated smooth muscle component of the wall. Activation of smooth muscle increased the elastic modulus when this was plotted as a function of strain. The active muscle exhibited a maximum elastic modulus of 3.99 A .08 x lo6 dynes/cm2 for the whole wall, or 12.66 x 106 dynes/cm2 for the estimated smooth muscle component of the tvall. Activation of smooth muscle decreased the elastic modulus when this was plotted as a function of pressure. This decrease leas attributed to the reduction in radius brought about by the active muscle.